1. Field of the Invention
The present invention relates to a fuel supply apparatus for controlling a fuel supply amount of an in-cylinder injection type internal combustion engine in which pressurized fuel is directly injected into a combustion chamber.
2. Description of the Related Art
A fuel supply apparatus used for an in-cylinder injection type internal combustion engine for a vehicle includes plural fuel injection valves for directly injecting fuel into respective cylinders of the internal combustion engine, a delivery pipe for supplying the fuel to the fuel injection valves, a high pressure fuel pump for supplying the pressurized fuel to the delivery pipe, a low pressure fuel pump for supplying the fuel to the high pressure fuel pump from a fuel tank, a control unit for controlling an injection timing of the fuel, an injection amount, and a discharge amount of the high pressure fuel pump, and the like. The high pressure fuel pump includes a cylinder, a piston which is driven by a rotating shaft of the internal combustion engine, for example, a pump driving cam provided at a cam shaft and reciprocates in the cylinder to suck the fuel into a pressure chamber at a suction stroke and pressure-sends the fuel in the pressure chamber to the delivery pipe at a discharge stroke, an electromagnetic valve which controls a fuel discharge amount from the pressure chamber and controls a fuel pressure in the delivery pipe by releasing the pressurized fuel in the pressure chamber to the low pressure side at a predetermined timing, and the like.
Since it is necessary to ON-OFF control the electromagnetic valve at a predetermined timing in accordance with a lift of the pump driving cam, the ON-OFF timing is controlled by using a rotation position signal indicating the position of the pump driving cam. The control of the ON-OFF position of the electromagnetic valve is required to be performed on the basis of a rotation position of a crank shaft of the internal combustion engine, that is, a crank angle. However, when an attachment position of the high pressure fuel pump has an error, or the pump driving cam is provided at a shaft different from the crank shaft, a deviation occurs in the cam lift relative to the crank angle and has a bad influence on the performance of the internal combustion engine. For the purpose of preventing the bad influence, various proposals for correcting the position deviation have been made.
A technique disclosed in patent document 1 (Japanese Patent No. 2836282 (pages 2 to 4, FIGS. 1, 2 and 5)) relates to correction of the attachment position. According to the technique disclosed in this document, in a fuel injection apparatus for a diesel engine having a common rail (delivery pipe), in order to prevent a bad influence on the performance of an internal combustion engine by correcting a deviation of a cam lift relative to a crank angle at time of trouble of a common rail pressure sensor, an engine rotation sensor for detecting a rotation angle of a crank shaft is provided at the crank shaft of the internal combustion engine, an attachment position error angle of a fuel pump is detected by a comparison between a specific crank position by the engine rotation sensor and a rotation position by a cylinder identification sensor provided at a cam shaft for driving the fuel pump, and power application to a spill electromagnetic valve is controlled in consideration of the attachment position error angle, so that an attachment error is corrected and high pressure fuel is pressure-sent to the common rail.
In the patent document 1, the correction of the attachment error is performed as described above. However, in this related art, since the phase difference between the signal of the cylinder identification sensor provided at the cam shaft for driving the fuel pump and the specific position signal of the engine rotation sensor provided at the crank shaft is merely detected, an attachment error of the fuel pump relative to a pump driving cam provided at the cam shaft can not be corrected, and the error in the discharge fuel amount relative to the delivery pipe can not be completely corrected. When the error occurs in the discharge fuel amount, the fuel pressure in the delivery pipe is not controlled to a predetermined pressure. Thus, an error occurs also in the amount of fuel injected from a fuel injection valve, and a predetermined air-fuel ratio is not obtained, and as a result, the combustion of the internal combustion engine is deteriorated and the performance (traveling performance of a vehicle) and exhaust gas are deteriorated.